Trabeculectomy Glaucoma Surgery

Aug 4, 2015

Trabeculectomy Glaucoma Surgery. Part 3 of 12 of “What’s New In Glaucoma Surgery” Presentation, a continuing education course for Optometrists presented by Patient-Focused Ophthalmologist, Dr. David Richardson on May 20, 2015.

Trabeculectomy Surgery for Glaucoma

So now moving to really what is the mainstay of glaucoma surgery here in the US- and I want to go through all the (kind of) basics of where we are before we get into the new stuff because this is really going to set up the stage for why newer glaucoma surgeries are so interesting and are really exciting.

So, Trabeculectomy is traditionally what we offer to patients who have failed drops, failed SLT, they’re advancing their glaucoma and traditionally the glaucoma has to be pretty severe, at least moderate to severe. You wouldn’t offer Trabeculectomy to somebody with mild glaucoma or just ocular hypertension and why? Well because what you’re doing is – there’s no other way to say, it’s pretty barbaric. You’re creating a fistula in the eye. Now I’ve got (general surgery) colleagues of mine, and they just think that we’re crazy in Ophthalmology, “The whole rest of Medicine tries to close fistulas when they appear spontaneously in the body. You guys – what are you doing? You’re creating fistulas and trying to keep them open!” And indeed that’s what we’re trying to do.

But, you have to recognize historically that Trabeculectomy was actually a step forward from what was done before Trabeculectomy. Before 1968, penetrating procedures were full thickness procedures. You basically poked a hole in the eye and you let the fluid drain underneath the conjunctiva which resulted in not surprisingly somebody going from a pressure that was too high to too low. And then it’s gone down, they went right back up where they were. So, the procedures weren’t very effective.

Now, as with Argon Laser Trabeculoplasty, Trabeculectomy was an accidental discovery. Doctor Cairns, back in 1968 developed a procedure. The intent of which, was too open up a flow from the anterior chamber through a Trabeculectomy – so truly just a removing a portion of the trabeculum, intro the canal and out the drainage system. He wanted to establish physiologic drainage. But what happened in his paper that he published was that the patients who failed… and his definition of failure was a bleb was created. Because if the bleb was created clearly the flow is not physiologic flow… Oddly enough those patients who developed a bleb – a cyst on the surface in the eye, were the ones whose pressures dropped and successfully had treated glaucoma. So what was revolutionary at the time was really, this right here – the flap. What was called a guarded flow. So instead of just being a hole in the eye this flap that was created in the sclera and then laid back down allowed some restriction of flow which had not been done before. So ironically, a surgical failure became the mainstay of glaucoma surgery for the world for the next 50 years.

But there are problems with Trabeculectomy, and we all know what they are, right? Trabeculectomy is hard to control. You can put this flap down but it’s all done by hand. And the restriction of flow is all- you know, “guesstimated”. So you can end up with pressures that are too high, too low. If pressures are too low, you can end up with hypotony maculopathy. So, a potentially, permanent loss of vision from pressures being too low- how’s that for a trade off?

The success of Trabeculectomy is entirely dependent upon the bleb. If you don’t have a bleb, you fail. So, of course, that meant that we had to develop all of these methods of keeping the body from doing what it naturally wants to do which is heal itself. So what do we do? We throw “poisons” (what we call anti-metabolites because poison doesn’t sound good). We throw anti-metabolites such as Mitomycin-C, 5-FU, unto this patient’s eye during surgery and then that keeps the eye from healing Well, I don’t know about you but most the time my body has healed me. It’s been a good thing, right? And indeed when we keep the eye from Healing what allows that bleb to stay also allows bacteria to potentially enter, break through this tissue which can’t heal and so patients who have Trabeculectomy are in lifetime risk infection. That infection that risk never goes away as long as they have an active bleb so their Trabeculectomy is working, by definition. They are at risk for infection.

Now in the past this may not have been a big deal. Why? Because most people who get glaucoma are a bit older Back before the baby boomers, you’re older, you’re in a rocker, you’re in bed, watching TV, I mean this you know people weren’t as active. Well now we’ve got all these active seniors with glaucoma and you know having something that could give them a lifetime risk of infection or limit their lifestyles is not something they’re going to be entrusted in having, right? I mean I just had a patient of mine who is in his 60s. He’s big wave surfer. He surfs waves better twice as high as the ceiling. You tell surfer that he’s going to have to stop surfing; you might as well just give them an overdose of morphine. Because he’s not going to want to live. So this surgery which has been with us for fifty years is now no longer an appropriate surgery for many of our patients. And so we really need something else.